Lecture 6 Flashcards
Definition of memory
The ability to store information, to consolidate it, and to retrieve it at a later point in time.
Clive Wearing
No hippocampal-dependent formation of long-term memory.
- Anterograte and retrograde amnesia.
- He is left with a few seconds of memory.
Items have to pass through 3 stages before they can be remembered
- Sensory memory
- Short term memory
- Long term memory
Sensory memory
Kept for a few seconds or less.
Short term memory
Non-sensory (recoded) information can enter the STM where it is kept between 15-20 seconds and fades without rehearsal.
- Repetition can ensure that information is retained in STM.
- The average number of meaningful elements we can hold is 7 (+/- 2),
Long term memory
If information is retained long enough in STM chances increase for storage in LTM.
- Spans hours to years.
- During recall information is retrieved from LTM to STM.
Visual sensory memory (iconic memory)
A fast decaying store of visual information.
- Iconic memory decays in about +-1 second (max).
Roger Sperling
- A grid of 12 letters presented for 50 ms cannot be successfully recalled (4-5 items).
- When a tone was presented after the grid informing patients about the row of letters that needed to be recalled (partial report cueing technique), recall improved.
- When the tone was delayed, performance dropped.
Auditory sensory memory (echoic memory)
A fast decaying auditory information.
- Echoic memory decays in about 5 seconds.
Primacy and recency effect
(when is it larger?)
Items at the beginning and the end of the list are remembered better than items in the middle.
- Recency is larger for auditory.
Chunking
Combining small pieces of information into clusters (e.g., phone numbers).
- Meaningful chunks often have an LTM component.
Working memory components (Baddeley & Hitch)
- Visuospatial sketchpad.
- Phonological loop.
- Central executive.
- Episodic buffer
Visuospatial sketchpad
For visual and spatial information.
- Necessary for mental rotation.
Phonological loop
~2 seconds that stores verbal information and maintains information via articulatory rehearsal.
- A loop expressed in time rather than in the number of items explains why long spoken words are harder to remember.
Central executive
Controls both phonological loop and visuospatial sketchpad.
An attentional system for coordination and output (action).
- Informed by the episodic buffer.
Episodic buffer
A temporary storage where information from LTM is integrated with STM.
Info in LTM is stored in 3 codes
- Verbal
- Visual
- Motor
Verbal (LTM code)
Semantic level (meaning)
Visual (LTM code)
Mental images that are not easily translated into language (like faces).
- Related to photographic memory and eidetic memory.
Motor
Motor programs that underlie activities such as speaking, walking, etc.
3 stages of remembering
- Encoding
- Storage
- Retrieval
Encoding
Transforming information into an enduring memory.
Storage
Maintaining memories over time.
Retrieval
Bringing stored information back into consciousness.
Use of schemas
Mental models of the world that helps us to encode information in a meaninful way (for us).
Elaborative encoding
Relating new information to knowledge that is already in memory.
- Verbal memory increases with processing depth.
Visual imagery encoding
Storing new information by converting it into mental pictures.
- When objects in a visual scene interact, they become easier to remember.
Organisational encoding
Categorising items based on relationships between them.
- E.g., a waitress categorises an order based on drinks, main courses and desserts, whereas the restaurant guests would organise items based on individuals.
- Recall improves when items are organised into multi-level categories.
Wilder Penfield
Canadian neurosurgeon who performed the first brain surgeries on patients with epilepsy. He stimulated a consciously awake patient’s brain with electrical current. By doing so, he discovered the motor and somatosensory cortex (the homunculi), but also that stimulation of the temporal cortex could evoke ‘lively memories’.
Karl Lashley
Studied the engram (the physical representation of a memory trace) by removing parts of the brain in animals and subsequently examined whether they had forgot earlier trained responses or whether learning became impaired.
- Rats were trained to find exits in a maze.
- Lesions affected acquisition and retention of knowledge, but the location of the removed part of the cortex did not affect performance.
Patient HM
In 1953, there was an accidental breakthrough: The case of Henry Molaison who had his hippocampus removed. He was unable to form new memories - anterograde amnesia
Hebb’s rule
What fires together, wires together.
Long term potentiation (LTP)
Where is it critical?
A persistent strengthening of synapses based on patterns of activity.
- Is critical in the hippocampus for memory formation.
Initiating LTP (+ blocking)
Glutamate from presynaptic (sending) neurons must attach to the NMDA receptors in the postsynaptic (receiving) neuron.
- When the post synaptic neuron is not excited, its NMDA receptors are blocked and LTP cannot happen.
Von Restoroff effect
Distinctive events are easier to remember.
- 4 8 1 7 A 5 3
- The A is easier to remember.
Encoding specificity principle (Tulving & Thomson)
A retrieval cue is most effective when it closely matches the original encoding context.
